Hi Prakriti,

To get admission in  National Institute of Open Schooling for class 12th examinations you need to register yourself online on official website of NIOs. After completion of registration process, the NIOS Admission is valid for five years, and student is given a maximum of  9 attempts to complete the course in NIOS Admission period.

For more details, visit the link below:

https://school.careers360.com/articles/nios-admission

Good Luck